doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Pressure vs recoil in old guns

What we're neglecting here, I think, where pressure is concerned is that a burst is not the ONLY possible negative result of shooting overpressure loads. That's the "shade tree gunsmith" view of proof: Work up a heavy load, put it in the gun, secure the gun to a tire, tie a string to the trigger, and go hide behind a tree. If the barrel doesn't burst or the gun otherwise fly to pieces, you're good to go. But that's not the way proof is done by the proofhouses. They also do something called "view" or "inspection", measuring for minute changes that may have occurred after firing--even if the barrels are still intact. If proofloads--which are, obviously, far in excess of service pressure--can cause such minute changes without resulting in catastrophic failure, than why cannot a SAAMI max load of 11,500 psi also cause minute changes (especially if used thousands of times) in a gun with a designed service pressure of 9,500 psi? If pressure is not an issue but recoil is, then that means I'm better off shooting a 1 oz load using 18.5 grains of Red Dot in an STS hull, 10,900 psi/1255 fps (courtesy of the Alliant book) rather than a 2 1/2" Eley Hawk VIP Game, 1 oz, 1300 fps--the latter producing higher recoil because of the greater velocity (but loaded to the lower CIP service pressure standard).

I think we also need to remember, especially as we approach SAAMI max service pressure (as in the above example) that although many of the loads Sherman Bell tested in his DGJ article showed a pressure increase of only a few hundred psi when fired in a short chamber, others approached (and at least one even exceeded) an increase of 1,000 psi. Factor in the variation from one reload to another, you could end up well over SAAMI max service pressure--and, worst case, not that far below original proof pressure of an older shotgun. (Which is why it's a very good idea to err on the side of caution when reloading for vintage guns. Fortunately, that's very easy to do for the 12ga in particular.)